ATOMIC_CAS(9F) Kernel Functions for Drivers ATOMIC_CAS(9F)


NAME


atomic_cas, atomic_cas_8, atomic_cas_uchar, atomic_cas_16,
atomic_cas_ushort, atomic_cas_32, atomic_cas_uint, atomic_cas_ulong,
atomic_cas_64, atomic_cas_ptr - atomic compare and swap operations

SYNOPSIS


#include <sys/atomic.h>

uint8_t atomic_cas_8(volatile uint8_t *target, uint8_t cmp, uint8_t
newval);


uchar_t atomic_cas_uchar(volatile uchar_t *target, uchar_t cmp, uchar_t
newval);


uint16_t atomic_cas_16(volatile uint16_t *target, uint16_t cmp, uint16_t
newval);


ushort_t atomic_cas_ushort(volatile ushort_t *target, ushort_t cmp,
ushort_t newval);


uint32_t atomic_cas_32(volatile uint32_t *target, uint32_t cmp, uint32_t
newval);


uint_t atomic_cas_uint(volatile uint_t *target, uint_t cmp, uint_t newval);


ulong_t atomic_cas_ulong(volatile ulong_t *target, ulong_t cmp, ulong_t
newval);


uint64_t atomic_cas_64(volatile uint64_t *target, uint64_t cmp, uint64_t
newval);


void *atomic_cas_ptr(volatile void *target, void *cmp, void *newval);


DESCRIPTION


These functions enable a compare and swap operation to occur atomically.
The value stored in target is compared with cmp. If these values are
equal, the value stored in target is replaced with newval. The old value
stored in target is returned by the function whether or not the
replacement occurred.

RETURN VALUES


These functions return the old of *target.

ERRORS


No errors are defined.

CONTEXT


These functions can be called from user, interrupt, or kernel context.

ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Committed |
+--------------------+-----------------+

SEE ALSO


atomic_add(9F), atomic_and(9F), atomic_bits(9F), atomic_dec(9F),
atomic_inc(9F), atomic_or(9F), atomic_swap(9F), membar_ops(9F),
attributes(5), atomic_ops(3C)


January 16, 2006 ATOMIC_CAS(9F)